From: Stefan Metzmacher <metze@samba.org>
Date: Wed, 23 May 2018 10:03:02 +0000 (+0200)
Subject: vfs_btrfs: make use of become_user_by_fsp() in order to switch between src and dst fsp
X-Git-Tag: tevent-0.9.37~293
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2d75da9f61f16eac3c137e16f98e16f4022b79b0;p=thirdparty%2Fsamba.git

vfs_btrfs: make use of become_user_by_fsp() in order to switch between src and dst fsp

We can use become_user_by_fsp()/unbecome_user() as it spans only parts of
the btrfs_offload_write_send() function and never goes async in between.

This may matter if at least one share uses "force user".

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
---

diff --git a/source3/modules/vfs_btrfs.c b/source3/modules/vfs_btrfs.c
index 515859d6b90..a11cb66d8e7 100644
--- a/source3/modules/vfs_btrfs.c
+++ b/source3/modules/vfs_btrfs.c
@@ -199,7 +199,26 @@ static NTSTATUS btrfs_offload_read_recv(struct tevent_req *req,
 struct btrfs_offload_write_state {
 	struct vfs_handle_struct *handle;
 	off_t copied;
+	bool need_unbecome_user;
 };
+
+static void btrfs_offload_write_cleanup(struct tevent_req *req,
+					enum tevent_req_state req_state)
+{
+	struct btrfs_offload_write_state *state =
+		tevent_req_data(req,
+		struct btrfs_offload_write_state);
+	bool ok;
+
+	if (!state->need_unbecome_user) {
+		return;
+	}
+
+	ok = unbecome_user();
+	SMB_ASSERT(ok);
+	state->need_unbecome_user = false;
+}
+
 static void btrfs_offload_write_done(struct tevent_req *subreq);
 
 static struct tevent_req *btrfs_offload_write_send(struct vfs_handle_struct *handle,
@@ -224,6 +243,7 @@ static struct tevent_req *btrfs_offload_write_send(struct vfs_handle_struct *han
 	bool handle_offload_write = true;
 	bool do_locking = false;
 	NTSTATUS status;
+	bool ok;
 
 	req = tevent_req_create(mem_ctx, &state,
 				struct btrfs_offload_write_state);
@@ -233,6 +253,8 @@ static struct tevent_req *btrfs_offload_write_send(struct vfs_handle_struct *han
 
 	state->handle = handle;
 
+	tevent_req_set_cleanup_fn(req, btrfs_offload_write_cleanup);
+
 	status = vfs_offload_token_db_fetch_fsp(btrfs_offload_ctx,
 						token, &src_fsp);
 	if (tevent_req_nterror(req, status)) {
@@ -289,6 +311,13 @@ static struct tevent_req *btrfs_offload_write_send(struct vfs_handle_struct *han
 		return tevent_req_post(req, ev);
 	}
 
+	ok = become_user_by_fsp(src_fsp);
+	if (!ok) {
+		tevent_req_nterror(req, NT_STATUS_ACCESS_DENIED);
+		return tevent_req_post(req, ev);
+	}
+	state->need_unbecome_user = true;
+
 	status = vfs_stat_fsp(src_fsp);
 	if (tevent_req_nterror(req, status)) {
 		return tevent_req_post(req, ev);
@@ -307,17 +336,24 @@ static struct tevent_req *btrfs_offload_write_send(struct vfs_handle_struct *han
 					num,
 					READ_LOCK,
 					&src_lck);
+		if (!SMB_VFS_STRICT_LOCK_CHECK(src_fsp->conn, src_fsp, &src_lck)) {
+			tevent_req_nterror(req, NT_STATUS_FILE_LOCK_CONFLICT);
+			return tevent_req_post(req, ev);
+		}
+	}
+
+	ok = unbecome_user();
+	SMB_ASSERT(ok);
+	state->need_unbecome_user = false;
+
+	if (do_locking) {
 		init_strict_lock_struct(dest_fsp,
-				       dest_fsp->op->global->open_persistent_id,
+					dest_fsp->op->global->open_persistent_id,
 					dest_off,
 					num,
 					WRITE_LOCK,
 					&dest_lck);
 
-		if (!SMB_VFS_STRICT_LOCK_CHECK(src_fsp->conn, src_fsp, &src_lck)) {
-			tevent_req_nterror(req, NT_STATUS_FILE_LOCK_CONFLICT);
-			return tevent_req_post(req, ev);
-		}
 		if (!SMB_VFS_STRICT_LOCK_CHECK(dest_fsp->conn, dest_fsp, &dest_lck)) {
 			tevent_req_nterror(req, NT_STATUS_FILE_LOCK_CONFLICT);
 			return tevent_req_post(req, ev);